Phenylene substituted polymeric dialkyl peroxides

ABSTRACT

Cyclic and acyclic phenylene substituted dialkyl peroxides most of which are in an acyclic polymeric form.

This invention relates to novel organic peroxides and their method ofpreparation. More particularly, it relates to cyclic and acyclicphenylene substituted dialkyl peroxides most of which are in an acyclicpolymeric form.

U.S. Pat. No. 3,419,577 discloses a group of aliphatic acyclic andcyclic organic peroxides having internal peroxide groups includingorganic peroxide polymers formed by etherifying an aliphatic diol withan aliphatic dihydroperoxide. The present compositions include adifferent group of polymeric and cyclic structures with the furtherdifference that the instant peroxides contain phenylene substitution.

More particularly, the present invention provides organic peroxidesselected from the group consisting of: ##STR1## wherein ##STR2##REPRESENTS A 1,4 OR 1,3 RING ATTACHMENT, A represents --CH₂ --CH₂ -- or--C.tbd.C--, and n is a positive integer from 1-5.

Preferred peroxides are obtained when in Formula I the ring attachmentsare in the 1,4 positions, A is --CH₂ --CH₂ -- and n is 2-4. Otherpreferred structures in relation to Formula I are when the ringattachments are in the 1,3 positions and A is --CH₂ --CH₂ -- and n is1-2. Another group of preferred structures relative to Formula I is whenthe ring attachments are in the 1,4 positions, A is --C.tbd.C-- and n is2-4.

With respect to Formula II, preferred peroxides are obtained when thering attachments are in the 1,4 positions, A is --CH₂ --CH₂ -- and n is1-3. Within this latter class, a preferred structure in relation toFormula II is when the predominant species has the formula in which n is2.

With respect to Formula III, preferred peroxides are obtained when thering attachments are in the 1,4 positions, A is --CH₂ --CH₂ -- and n is1-3. Within this latter class, a preferred structures relative toFormula III is when the predominant species has the formula in which nis 2.

With respect to Formula IV, preferred compositions have the ringattachments in the 1,4 positions.

In the preferred embodiment the organic peroxides of this invention areprepared by an etherification reaction under conditions similar to thatdescribed in U.S. Pat. No. 3,419,577. In general, the reaction providesa mixture of compounds. If desired, the mixture can be isolated intoindividual components. However, it is generally unnecessary to make sucha separation and the mixtures may be used as such for most applications.

More particularly, the present compounds are preferably formed byetherifying at least one diol selected from1,4-bis(hydroxyisopropyl)benzene of the formula: ##STR3## and1,3-bis(hydroxyisopropyl)benzene of the formula: ##STR4## with at leastone dihydroperoxide selected from 2,5-dimethyl-2,5-dihydroperoxyhexaneof the formula: ##STR5## 2,5-dimethyl-2,5-dihydroperoxyhexyne-3 of theformula: ##STR6## and 3,6-dimethyl-3,6-dihydroperoxyoctane of theformula: ##STR7##

The polymeric peroxides of Formulas I and IV are obtained by reactingthe selected diol and the selected dihydroperoxide in equimolarquantities. The polymeric peroxide of Formulas II and III are obtainedby reacting the diol and the dihydroperoxide in a 1:2 or 2:1 molarratio. The peroxides of Formula II are obtained by reacting two moles ofdihydroperoxide with one mole of diol. Conversely, Formula III isobtained by reacting two moles of diol with one mole of dihydroperoxide.

Although the foregoing method of preparing the instant new compositionsis preferred, it is also possible to prepare the same peroxides withalternative starting materials. For example, the following reactionswill also result in the novel peroxides of Formula I of this invention.##STR8##

Products of the present invention have utility as crosslinking orvulcanizing agents of polyolefins or various elastomers. They can alsobe used as high temperature catalysts for the curing of unsaturatedpolyester resins with crosslinkable monomers.

The following experimental work illustrates preparation and utility ofthe present compositions. In the work reported below comparisons havebeen made against 1,3-bis(t-butyl peroxyisopropyl)benzene because it isa commercial peroxide with a nonpolymeric structure somewhat similar tothe repeating unit from Formula I, that is ##STR9## In addition,2,5-dimethyl-2,5-di(t-butyl peroxy)hexyne-3 was used for comparisonbecause it is a commercial peroxide used to crosslink high densitypolyethylene (HDPE).

EXAMPLE 1 Reaction Between V and VI

A solution of 7.76 g (0.04 mole) of 1,4-bis(hydroxyisopropyl) benzene(V) was prepared in 45 ml of warm glacial acetic acid. This solution wasthen added to 7.24 g of 98.27% (0.04 mole)2,5-dimethyl-2,5-dihydroperoxy hexane (VI) dissolved in 45 ml glacialacetic acid in a 125 ml round bottom flask equipped with a mechanicalstirrer and thermometer. The mixture was cooled to 15° C. Then 0.1 g of70% HClO₄ in 10 ml glacial acetic acid was added in several portionsover about a one-minute period. Within one minute after completion ofthe acid addition, the solution began to turn cloudy, and a solid beganto precipitate. The suspension was stirred for an additional 2 hours at15° C. and then dumped into 200 ml of ice water. The aqueous layer wasremoved by suction, additional water and NaHCO₃ added to bring the pH toabout 6, and the solid product was finally collected by filtration anddried in a vacuum oven. Yield: 12.3 g (91.5%). Characterization of thisproduct is shown in Table 1 as entry 1(b). The other dialkyl peroxidesshown in Table 1 were prepared by essentially the same method bysubstituting the necessary amounts of the other two alkyldihydroperoxides (VII and VIII) or 1,3-bis(hydroxyisopropyl) benzene(Va).

Experimental

1. Press Molding of Low Density Polyethylene (LDPE)

The desired amount of peroxide was dryblended into 30.0 g of powderedLDPE resin¹) by stirring for 5 minutes with a spatula. Aluminum foil wasused to cover the platens. Platen temperatures on the press were checkedwith a surface pyrometer and were 320± 5° F. (160° C.). Cure time was 30minutes. It started when the ram gauge read 1,000 PSIG. Final pressurewas between 4,000-8,000 PSIG. At the end of the cure time the pressurewas released immediately. Trays were removed from the molds and cooledquickly in a water bath. The aluminum foil was removed from the tray byimmersing it in approximately 18-20% HCl solution.

To determine the %wt gel, an approximately 0.3 g sample was cut into 6-7pieces and placed inside a stainless steel screen pouch. These poucheswere extracted in 2 liters of boiling xylene containing 10 g ofPlastonox 2246 anti-oxidant for 16 hours and then dried in an oven at170° C. for 4 hours. Results are shown in Table 2.

The %wt gel was calculated by the following formula: ##EQU1## Where: W₁= wt. of sample, g.

W₂ = wt. of sample + pouch, g.

W₃ = wt. of sample + pouch after extraction, g.

W_(b1) = blank value for resin without peroxide.

2. Crosslinking or Vulcanizing Various Resins in a Torque Rheometer

A Brabender Plasticorder at a rotor speed of 30 RPM was used for thesetests. For polyolefins, the Roller-6 blades were used; for theelastomers, the Cam blades were used. The desired weight of a particularresin was added to the Plasticorder maintained at the desiredtemperature. At either 12 or 16 minutes, the correct weight of peroxideon a carrier or in n-hexane solution was added directly to the mixinghead. Net torque is equal to the maximum torque minus the torque atperoxide addition. Time to reach maximum torque is the time at maximumtorque minus the time of peroxide addition. It an additive was used, itwas added to the mixing head after 7 minutes. The following amounts ofvarious resins were used in these tests:

    ______________________________________                                        Resin                Wt, g      Table                                         ______________________________________                                        1.  Union Carbide DYNH low density                                                polyethylene (LDPE) pellets                                                                        35 or 40   3                                         2.  USI Microthene "F"LDPE powder                                                 (peroxide carrier)    5         3                                         3.  Phillips Marlex BMN5565 high density                                          polyethylene (HDPE) pellets                                                                        40         4                                         4.  Copolymer Epsyn 4506 ethylene                                                 propylene diene rubber (EPDM)                                                                      40         4                                         5.  Dow 3614 chlorinated polyethylene                                             (CPE) powder         40         4                                         ______________________________________                                         Footnote:                                                                     In Table 3, when a carrier other than Burgess clay is used with the           polymeric dialkyl peroxides, there is an induction period after the           peroxide is added when no crosslinking occurs. The reason for this            phenomenon is unknown.                                                   

    Table 1      Dialkyl Peroxides from α, α'-Dihydroxy Diisopropyl Benzene     and Various Alkyl Dihydroperoxides Using HClO.sub.4 as an Acid Catalyst          Chromatographic Reaction  % Yield  Active Oxygen Analyses Analysis     (Area %).sup.1)  Mole Time Temp., of  M.P., Total  Polymeric Starting     Reactants Ratio Hrs. ° C. Product M.W. °      C. A.O.           OOH A.O. Peroxides Material       1. V + VI (a) 1:1 2 15 90.2 1097 avg. 92-102  9.15 avg. 1.09 96 4  (b)     1:1 2 15 91.5 1075 86-96  9.86 avg. 1.37 avg. 94 6  (c) 1:2 2 15 70.8     763 85-91 10.75 avg. 3.24 avg. 96 4  (d) 2:1 2 15 78.8  748 80-86  7.76     avg. 0.25 avg. 96 4 2. Va + VI (a) 1:1 2.5 15-25 ND.sup.2)  475 liquid     6.46 avg. 1.18    (b)1:15.515- 20 ND  525 same  6.64 1.16  95 5 3. V +     VII  1:1 93 15-20 ND  849 73-75  7.05.sup.3) 0.57 93 7 4. V + VIII  1:1     2 15-20 ND  305 liquid     .sup.1) Products from items 1-3 were done by GPC; product from item 4 was     done by LC.     .sup.2) Not determined     .sup.3) --.tbd.C-- group interferes with Total A.O. analysis.     .sup.4) Approximately 40% is the aromatic diol and 60% is the alkyl     dihydroperoxide.

                  Table 2                                                         ______________________________________                                        Crosslinking LDPE by Press Molding                                            at 320° F. (160° C. for 30 Minutes with Various Peroxides       Peroxide    M.W.       phr.sup.1)                                                                             %wt Gel                                       ______________________________________                                        1.  Blank       --         --     0.5                                         2.  BTBIB.sup.2)                                                                              --         2.5    91.1                                        3.  V + VI.sup.3)                                                                             1097       2.5    56.9, 58.0                                  4.  Va + VI.sup.3)                                                                            525        2.5    35.8                                        ______________________________________                                         .sup.1) On a 100% purity basis for BTBIB and on an "as-is" basis for othe     peroxides.                                                                    .sup.2) 1,3-Bis(t-butyl peroxyisopropyl) benzene.                             .sup.3) Peroxide obtained from reaction of equimolar amounts of each          indicated reactant.                                                      

                                      Table 3                                     __________________________________________________________________________    Crosslinking LDPE in the Brabender Plasticorder with Various Peroxides                                     Induction                                                                             Time to                                                           Head                                                                              Period  Complete                                                                             Total Time                                         Peroxide                                                                              Temp.,                                                                            After Adding                                                                          Crosslinking,                                                                        to Maximum                                                                           Net Torque,                Peroxide.sup.1)                                                                      M.W.   phr.sup.2)                                                                       Carrier ° C.                                                                       Peroxide, Min.                                                                        Min.   Torque, Min.                                                                         mg.                        __________________________________________________________________________    1. BTBIB.sup.3)                                                                      --     2.5                                                                              LDPE Powder                                                                           160 --      --     5.2, 6.0                                                                             1170, 1150                 2. V + VI                                                                            (a) 1097 avg.                                                                        2.5                                                                              same    160 12.5    13.5   26.0   1320                                     2  same    170 3.0, 4.0                                                                              9.5, 9.0                                                                             12.5, 13.0                                                                           1220, 1290                        (b) 1075                                                                             2.5                                                                              Burgess clay                                                                          160 --      --     15.5   1360                                     2  same    170 --      --     4.5, 5.2                                                                             1200, 1230                 3. V + 2 VI                                                                          763    2  LDPE Powder                                                                           170 2.0     10.0   12.0   1010                       4. 2 V + VI                                                                          748    2  same    170 1.5     11.5   13.0   1160                       5. Va + VI                                                                           475    2  n-hexane                                                                              170 8.0      6.0   14.0    700                       6. V + 849I   2  Burgess clay                                                                          170 --      --     30.0   1000                       __________________________________________________________________________     .sup.1) Peroxide used was that obtained from reaction of reactants in mol     ratios indicated.                                                             .sup.2) On a 100% purity basis for BTBIB and on an "as-is" basis for the      other peroxides. .sup.3) 1,3-Bis(t-butyl peroxyisopropyl) benzene        

                                      Table 4                                     __________________________________________________________________________    Crosslinking Various Polymers in the Brabender Plasticorder                   with Various Peroxides on Burgess Clay                                                             Additive,                                                                             Head Temp.,                                                                          Time to Max.                                                                         Net Torque                         Peroxide.sup.1)                                                                        M.W.                                                                              phr.sup.2)                                                                       Polymer                                                                            phr     ° C.                                                                          Torque, Min.                                                                         mg.                                __________________________________________________________________________    1. BTBIB.sup.3)                                                                        --  7.5                                                                              EPDM --      160    2.0    460                                2. V + VI                                                                              1075                                                                              7.5                                                                              EPDM --      160    3.2    520                                3. BTBIB --  7.5                                                                              CPE  2 Mark WS                                                                             160    3.0    260                                                     3 Mark 224                                               4. V + VI                                                                              1075                                                                              7.5                                                                              CPE  same as above                                                                         160    5.0    420                                5. DMDTBH-3.sup.4)                                                                     --  0.5.sup.5)                                                                       HDPE --      190    8.8    3480                               6. V + VIII                                                                             849                                                                              1.25                                                                             HDPE --      190    7.3    2340                               __________________________________________________________________________     .sup.1) Peroxide used was that obtained from reaction of reactants in mol     ratios indicates.                                                             .sup.2) On a 40% active basis                                                 .sup.3) 1,3-Bis(t-butyl peroxyisopropyl) benzene                              .sup.4) 2,5-Dimethyl-2,5-di-t-butyl peroxy                                    .sup.5) On a 100% purity basis, diluted in n-hexane                      

                  Table 5                                                         ______________________________________                                        Hot-Block Gel Tests with Various Peroxides                                    in Hatco GR-14010 Unsaturated Polyester Resin at 275° F.               Catalyst Concentration:                                                                     1.0% wt (100% purity basis)                                                       Gel Time, Exotherm                                                                              Peak Temp.,                               Peroxide.sup.1)                                                                         M.W.    Min.      Time, Min.                                                                            ° F.                               ______________________________________                                        1. BTBIB.sup.2)                                                                         --      2.12      2.68    367.5                                                       2.06      2.56    370                                       2. V + VI 1097    2.68      3.11    381                                                         2.50      2.93    368                                       3. Va + VI                                                                              500     2.21      2.66    373                                                         2.22      2.72    378                                       4. V + VII                                                                              849     2.67      3.22    385                                                         2.59      3.18    386                                       5 V + VIII                                                                              305     2.45      2.92    375                                                         2.43      2.92    377.5                                     ______________________________________                                         .sup.1) Peroxide used was that obtained from reaction of reactants in mol     ratios indicated.                                                             .sup.2) 1,3-Bis(t-butyl peroxyisopropyl) benzene                         

We claim:
 1. Organic peroxides selected from the group consisting of:##STR10## wherein ##STR11## represents a 1,4 or 1,3 ring attachment, Arepresents --CH₂ --CH₂ -- or --C.tbd.C--, and n is a positive integerfrom 1-5.
 2. Organic peroxides in accordance with claim 1 wherein theselected peroxide has the formula of subparagraph (a) in which the ringattachments are in the 1,4 positions and in which A is --CH₂ --CH₂ --and n is 2-4.
 3. Organic peroxides in accordance with claim 1 whereinthe selected peroxide has the formula of subparagraph (a) in which thering attachments are in the 1,3 positions, A is --CH₂ --CH₂ -- and n is1-2.
 4. Organic peroxides in accordance with claim 1 wherein theselected peroxide has the formula of subparagraph (a) in which the ringattachments are in the 1,4 positions, A is --C.tbd.C-- and n is 2-4. 5.Organic peroxides in accordance with claim 1 wherein the selectedperoxide has the formula of subparagraph (b) in which the ringattachments are in the 1,4 positions, A is --CH₂ --CH₂ -- and n is 1-3.6. Organic peroxides in accordance with claim 5 wherein the predominantspecies has the formula in which n is
 2. 7. Organic peroxides inaccordance with claim 1 wherein the selected peroxide has the formula ofsubparagraph (c) in which the ring attachments are in the 1,4 positions,A is --CH₂ --CH₂ -- and n is 1-3.
 8. Organic peroxides in accordancewith claim 7 wherein the predominant species has the formula in which nis
 2. 9. Organic peroxides in accordance with claim 1 wherein theselected peroxide has the formula of subparagraph (d) in which the ringattachments are in the 1,4 positions.